Recently, mobile devices have increasingly been manufactured with image capture devices such as cameras so that the functions of mobiles devices and cameras have converged in a single device. In order to provide added functionality, cameras in mobile device may be provided with an active sensor and a passive sensor. The reason why active sensors are used in mobile device is that there is a limit in how much depth information in images can be acquired by passive sensors. Active sensors, which output light that are reflected by objects in an image field, may do a better job of allowing the camera or an image sensor to detect depth information of the object, i.e. the distances of each object in the image field from the mobile device. However, active sensors may consume a large amount of power. Therefore, an efficient method of operating active sensors is required.
Methods that use active sensors to generate a depth map may include a Structured Light (SL) method and a Time of Flight (ToF) method as illustrated in FIGS. 1 and 2, respectively. The SL type illustrated in FIG. 1 refers to a method of outputting an infrared light (IR) through a stripe or dot-shaped slit and detecting a change in an IR pattern through a camera. The detected IR pattern can be used to generate the depth map. The ToF type illustrated in FIG. 2 refers to a method of directly outputting the IR towards a target object and measuring the time it takes for the reflected light to return from the target object to the image sensor, and determining the distance of the target object from the sensor using the measured time. The determined distances can be used to generate the depth map.